Sidirokastro is a town in the Serres regional unit, Greece.
It is built near the fertile valley of the river Strymonas, on the bank of the Krousovitis River.
Sidirokastro is situated on the European route E79 and the main road from northern Greece (Thessaloniki) to Bulgaria. Sidirokastro is located 19 km to the northwest of the town of Serres, between the Vrontou and Angistro mountains (to the north) and the river Strymonas (to the west).
The town is crossed by the Krousovitis River, one of the Strymonas' tributaries, which divides the town into two sections. These sections are connected by two bridges: Stavrou and Kalkani.
The landscape is made even prettier thanks to the Maimouda rivulet and its miniature bridges.
Sidirokastro's population is a blend of indigenous people and descendants of the early 20th century waves of refugees from Asia Minor (people who sought asylum in Greece from the wars and conflicts of that period). Sidirokastro took in refugees from Melnik in 1913; from East Thrace (European Turkey) after the 1922 onslaught that followed the Greco-Turkish Wars in Asia Minor; from Pontus, Vlachs and people from all over Greece.
The Kerkini, Angistro and Orvilos mountain ranges form natural boundaries of the greater area and of Greece with neighbouring Balkan countries.
The area around Sidirokastro is rich in minerals (marble, lignite, manganese, copper, pyromorphite, iron, chromite, dolomite, uranium) and geothermal springs.
It has interesting sights, such as the medieval stone castle, Byzantine ruins, natural spas and beautiful nature.